Dynamo-electric machine.



IATENTED MAR. 27, 1906.

0. P. STEINMETZ. DYNAMO ELECTRIC MACHINE.

APPLICATION FILED JAN. 28, 1905. I

v Inventor Charles P. Steinmetz.

Witnesses.

CHARLES P. STEINMETZ, OF SUHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

DYNAMO-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented March 27, 1906.

. Application filed January 28, 1905. Serial N0..243,014

To all whom it may concern:

Be it known that I, CHARLES P. STEIN- METZ, a citizen of the United States, residing at Schenectady, in the county of Schenectady I and State of New York, have invented certain new and useful Improvements in Dynamo Electric Machines, of which the following is a specification.

' M invention relates to dynamo-electric mac nes of the commutator type, more particularly to' alternating current machines; and its object is to provide a novel arrangement of high resistance commutator leads which is exceedingly compact, durable, and accessible for repairs.

In alternating-machines of the commutator typle ithas been proposed heretofore to insert 'gh resistances in the connections between the commutator-segments and the armature-winding for the purpose of limiting the current flowing in an armature-coil when short-circuited by a brush- My invention relates to machines employ ing commutator-leads of this type.

r In one aspect my invention consists in providing the armature-body with a second set of slots more remote from the periphery than the slots carrying the main armature-conductors and in placing the high-resistance leads in these inner slots. With this arrangement the heat produced in the leads is conducted away by the armature-core without injury to the main armature-conductors.

In another aspect my invention consists in employing bifilar resistances extending through and supported in the armature-body. This gives an exceedingly compact arrangement and aiiords firm support for the leads and protects them from external injury. By making the resistances bifilar or double in ducedelectromotive forces in the leads are avoided. Since While the motor is running each lead is in circuit only momentarily, the leads may be made of very hi h resistance compared to the resistances of t 1e armatureconductors, es ecially if the leads are so arranged that tiie heat produced in them is Y rapidly conducted away; but if the motor fails to start when current is supplied to it the leads connectedv to the segments .which are 'under thebrushes are maintained continuously in circuit and under such conditions the commutator.

are liable to be burned out. Consequently it is important that the leads should be so arranged that they may be readily accessible for repairs.

My invention, more specifically considered,

consists in arranging the leads in holes in the armature-body independent of the slots containing the armature-conductors and in connecting the leads to the armature-coils at the end away from the commutator, so that they are readily accessible for repairs. Another feature of my invention consists in arranging the leads with greater cross-section at the portions where they extend beyond the end of the armature-body for connection to the armature conductors, since f the radiation from these parts is less eliective in carrying away the heat than the conduction from the po(ritions of the lead within the armaturebo y.

My invention will best be understood by reference to the accompanying drawings, in which Figure 1 shows a diagrammatic development of an armature-winding provided with commutator and commutator-leads arranged and connected in accordance with my invention. Fig. 2 is a detail in cross-section, showing" the arrangement of armature-coils and commutator-leads in the armature-body. Fig. 3 shows a side view, partly in cross-section, of an armature arranged in accordance with my invention; and Fig. 4 is an enlarged detail view showing the bifilar leads in crosssection.

In the drawings, A represents the armature, provided with a commutator C and the armature-coils a. The commutator is not connected to the armature-coils in the usual manner-that is, by leads directly connecting each commutator-segment with the adjacent end of an armature-coilbut instead each segment is connected to a lead 0, which extends through the bottom of the coil-slots to the other end of the armature and is there connected to one end of a terminal of a bifilar resistance 1', the other end of which is connected to the armature-coil at the end away from The leads 0 may be of higher resistance per unit of length than the armature-conductors, since each lead is in circuit only a fraction of'the time, and conse- ICO quently these leads are represented as of ances r, so that if the motor should refuse to start when the current is turned on the resistances r would be burned out rather than the leads 0. The resistances-r are shown of large cross-section compared to the leads 0, since these resistances are preferably made of high-resistance material, such as coppernickel. The resistances r are supported in the armature-body independent of the coilslot. (Clearly shown in Figs. 2 and 3.) IVith this arrangement the heat produced .in the resistances is efficiently conducted away by the metal of the armature-body and can pro duce no injury to the insulation of the armature-conductors, as would be the case if the resistances were placed in the same slots with the armature-coils. As clearly appears from Fig. 3, it would be impossible to get at the resistan'oustrips r at the commutator end without breaking several of the commutator connections and removing some of the end connections of the armature-coils. On the other hand, at the other end of the armature there are no obstructions in the way and the connections between those resistances and the coils c and leads 0 may be readily made. Furthermore, since the resistances are supported entirely independently of the armature-coils and coil-slots their withdrawal for renewal does not disturb the ar1nature-winding.

As shown in Fig. 3, the resistances r are formed with a larger cross-section at the portions which extend beyond the armature, since the heat is led away by radiation'less eiiectively from these portions than by conduction from the portions within the armaturebody.

, What I claim as new, and desire to secure I by Letters Patent of the United States, is-

1. In a dynamo-electric machine, a slotted armature, a winding in the slots, a commuta tor, and bifilar resistances supported in holes in the armature-body independent of said slots and inserted in the connections between said windings and the commutator-segments.

2. In a dynamo-electric machine, an armature provided with peripheral slots and holes below and independent of said slots, coils in said slots, a commutator, bifilar resistances supported 1n said holes and having their terimnals at the end of the armature away from Y the commutator, a connection from one terminal of each resistance to the adjacent end I tor-segment.

of an armature-coil, and a coimection from the other terminal of each resistance extending across the armature-body to a commuta- 4. In a dynamo-electric machine, an armature provided with peripheral slots and holes below and independent of said slots, coils in said slots, a commutator, bifilar resistances supported in said holes and having their terminals at the end of the armature away from' the commutator, a connection from one terminal of each resistance to the adjacent end of an armature-coil, and a connection from the other terminal of each resistance extending through one of said slots to a commutator-se ment.

5. n a dynamo-electric machine, an armature provided with peripheral slots and holes below and independent ofsaid slots, armature-coils in said slots, a commutator, leads of higher resistance per unit of length than said coils connected to said commutator and extending through said slots across the armature, and bifilar resistances of higher resist-. ance per unit of length than said leads supported in said holes and having their terminals connected to said coils and to said leads at the end of the armature away from the commutator.

6. In a dynamo-electric machine, a slotted armature, a winding in the slots, a commutator, and high-resistance leads supported in the armature body independently of said slots and inserted in the connections between said windings and the commutator-segments,.

the portions of said leads extending beyond the armaturebody being of greater crosssection than the portions within said body.

7. In a dynamo-electric machine, an armature provided with peripheral slots and holes below and independent of said slots, a winding in said slots, a commutator, and bifilar resistances supported in said holes connected to said windin and to said commutator, the

portions of said leads extending outside of said holes being of lower resistance per unit 10. In an electrical machine, a cylindrical,

. magnetizable core having a set of slots adj acent to. its periphery and a second set of slotscomparatively. remote from its periphery, of relatively low resistance and high resistance conductors located in said slots and connectsaid inner slots, each of said conductors beed in circuit with each other. ing'doubled upon itself and connected at one 11. In an electrical machine, a member end to a corresponding armature-coil and at having a cylindrical magnetizable core proits other end to .a commutator-bar. 3o

Vided with a circumferential set of slotsadja- 14. An electrical-machine core having concent to its outer surface, a circumferential set 1 centric sets of slots, those of one set being adof slots between said 0 ter set and the inner jacent to the surface, and of the proper numsurface of the core, relatively low resistance ber, form and dimensions to contain armaconductors located-1n said outer slots and turec0ils and those of the other set being of 35- relatively high resistance conductors conthe proper number, form and dimensions to nected thereto andlocated in said inner slots. contain resistance-leads for connection to the 12. n an electrical machine, the combiriaarmature-coils.

tion with a commutator of an armature hav 15. An electrical-machine core havin com ing core-slots adjacent to the surface of its centric sets of slots, in combination Wit two 40 core for the reception of coils, and a series sets of conductors of different resistance losaid inner slots and connecting the armaturesions, toits conductors. i 45 conductors to the commutator-bars. In Witness whereof I have hereunto set my n lan electrical machine, ai ariplatlure hand this 26th day'of January, 1905. I avin a aminated core rovide Wit s ots adjace nt to its outer surfd ce, and slots inter- CHARLES STEINMETZ' mediate its outer and its inner surfaces, ar- Witnesses: 25 mature-coils located in said outerslots, rela- BENJAMIN B. HULL,

tively high resistance conductors located in HELEN ORFORD. 

